Korean Journal of Biological Psychiatry

Objectives：Neurological soft signs have been regarded as endophenotypes associated with the genetic basis of schizophrenia. This study was to investigate the intra-familial correlations of the neurological soft signs according to their genetic loading.

Methods：Schizophrenic patients(N=14) were included, who had one parent with a family history of schizophrenia and the other without it. Genetic loading was determined by the patient's family history of schizophrenia using the Family Interview for Genetic Studies(FIGS). These parents were subdivided into two groups. The first group was designated as 'presumed carriers'(N=9) of genetic loading, who had one or more schizophreic first- or second-degree relatives. The second group was designated as 'presumed non-carriers'(N=11) of genetic loading, who had no schizophrenic first- or second-degree relatives. Normal controls(N=12) consisted of people without schizophrenic relatives. NSS were evaluated using the Neurological Evaluation Scale-Korean Version (NES-K), and the intra-familial correlations of NSS were tested using the Intra-Class Coefficients(ICC) method.

Results：The scores of Motor Coordination subdimension of NES-K were significantly correlated between the patients and their presumed carriers(ICC=.804, p=.016), but not significantly correlated between the patients and their presumed noncarriers. In other subdimensions of NES-K, no significant correlation were found between the patients and their parents regardless of the genetic loading. But, there were no statistically significant differences in the scores of Motor Coordination subdimension of NES-K between the patients and controls.

Conclusion：This study did not prove that the neurological soft signs might be an endophenotype of schizophrenia that cosegregate with the genetic loading. The future study using more subjects than this would be needed.

Keywords Schizophrenia;Neurological soft signs;Genetic loading;Intra-class coefficients.